PH Effect on the Growth of Bean Plants

Overview

Green beans are among the most forgiving of vegetables to grow. Give them warm soil amended with compost in late spring and they require little more than adequate watering to produce bountiful crops. Unless you know that your soil is very acidic or very alkaline, the best strategy is to grow a crop of beans and see how they perform. Chances are, they'll surprise you and do just fine.

Ideal Conditions

The ideal soil pH for green beans is slightly acidic, between 6.0 and 6.5, according to the National Gardening Association. But few garden soils naturally have the perfect soil. Many soils along the eastern and western coasts of the United States have acid soils, while the dry, mountainous regions of the west, mid west and south west often have alkaline soils. Fortunately, green beans tolerate soil ranges moderately lower or higher than the recommended range.

Acid Soils

Acidic soils (below 6.0) may reduce the availability of some nutrients, such as zinc, according to Iowa State University. Theoretically, these deficiencies might cause stunted growth or deformed pods, but beans aren't heavy feeders. With added fertilizer, they often grow well in spite of acidic soils. Additionally, acid soils make chemicals, such as fertilizers, herbicides and pesticides less soluble. These products are more prone to run-off and may pollute groundwater.

Alkaline Soils

In alkaline soils, several nutrients become bound in the soil, making them less available for plants. Beans are most likely to suffer iron deficiencies in alkaline soils. The main symptom of chlorosis in beans is yellowing of new growth, according to Texas Gardener.

Identification

A pH meter can inexpensively determine the pH level of your soil, although a soil test provides a complete analysis. Soil tests are available through commercial laboratories or county extension offices. These tests are reasonably priced and provide details on not only the pH level of the soil, but the amount of organic matter in the soil, as well as nutrients.

Considerations

Fixing acidic soil is fairly simple. Just add a few shovelfuls of lime, based on the results of a soil test, to the soil during garden preparation. Fixing very alkaline soil is a bit more difficult. Iron sulfate or chelated iron are two supplements routinely used to provide iron to plants in alkaline soils. Iron sulfate quickly becomes bound in the soil, making repeated applications necessary, according to Texas Gardener. Chelated iron is more soluble, but is also more expensive. Building raised beds and bringing in new soil might be the best long-term option.